diff options
| author | Petar Penkov <ppenkov@google.com> | 2018-12-02 20:18:19 -0500 |
|---|---|---|
| committer | Daniel Borkmann <daniel@iogearbox.net> | 2018-12-03 21:37:51 +0100 |
| commit | e3da08d057002f9d0831949d51666c3e15dc6b29 (patch) | |
| tree | 1e7a9ef1d6ad44355a50a26ef15a159fd807c72b /tools | |
| parent | de94b651eef38b44adc20057ab5eb6d4ca672169 (diff) | |
bpf: allow BPF read access to qdisc pkt_len
The pkt_len field in qdisc_skb_cb stores the skb length as it will
appear on the wire after segmentation. For byte accounting, this value
is more accurate than skb->len. It is computed on entry to the TC
layer, so only valid there.
Allow read access to this field from BPF tc classifier and action
programs. The implementation is analogous to tc_classid, aside from
restricting to read access.
To distinguish it from skb->len and self-describe export as wire_len.
Changes v1->v2
- Rename pkt_len to wire_len
Signed-off-by: Petar Penkov <ppenkov@google.com>
Signed-off-by: Vlad Dumitrescu <vladum@google.com>
Signed-off-by: Willem de Bruijn <willemb@google.com>
Acked-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Diffstat (limited to 'tools')
| -rw-r--r-- | tools/include/uapi/linux/bpf.h | 1 | ||||
| -rw-r--r-- | tools/testing/selftests/bpf/test_verifier.c | 32 |
2 files changed, 33 insertions, 0 deletions
diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h index 8050caea7495..0183b8e70a9e 100644 --- a/tools/include/uapi/linux/bpf.h +++ b/tools/include/uapi/linux/bpf.h @@ -2497,6 +2497,7 @@ struct __sk_buff { __u32 data_meta; struct bpf_flow_keys *flow_keys; __u64 tstamp; + __u32 wire_len; }; struct bpf_tunnel_key { diff --git a/tools/testing/selftests/bpf/test_verifier.c b/tools/testing/selftests/bpf/test_verifier.c index c3b038f26ece..b4b4a3f93639 100644 --- a/tools/testing/selftests/bpf/test_verifier.c +++ b/tools/testing/selftests/bpf/test_verifier.c @@ -14033,6 +14033,38 @@ static struct bpf_test tests[] = { .result_unpriv = REJECT, .result = ACCEPT, }, + { + "check wire_len is not readable by sockets", + .insns = { + BPF_LDX_MEM(BPF_W, BPF_REG_0, BPF_REG_1, + offsetof(struct __sk_buff, wire_len)), + BPF_EXIT_INSN(), + }, + .errstr = "invalid bpf_context access", + .result = REJECT, + }, + { + "check wire_len is readable by tc classifier", + .insns = { + BPF_LDX_MEM(BPF_W, BPF_REG_0, BPF_REG_1, + offsetof(struct __sk_buff, wire_len)), + BPF_EXIT_INSN(), + }, + .prog_type = BPF_PROG_TYPE_SCHED_CLS, + .result = ACCEPT, + }, + { + "check wire_len is not writable by tc classifier", + .insns = { + BPF_STX_MEM(BPF_W, BPF_REG_1, BPF_REG_1, + offsetof(struct __sk_buff, wire_len)), + BPF_EXIT_INSN(), + }, + .prog_type = BPF_PROG_TYPE_SCHED_CLS, + .errstr = "invalid bpf_context access", + .errstr_unpriv = "R1 leaks addr", + .result = REJECT, + }, }; static int probe_filter_length(const struct bpf_insn *fp) |